Liquid crystal display with zigzag shaped pixel and counter electrodes with notch formed in concave portion of pixel and counter electrodes

ABSTRACT

Pixel regions are formed on a liquid-crystal-side surface of one substrate out of respective substrates which are arranged to face each other in an opposed manner with liquid crystal therebetween, wherein each pixel region includes pixel electrodes having bent portions and counter electrodes which are arranged at positions where the pixel electrodes are shifted in parallel, the pixel electrode and the counter electrode are respectively constituted of two electrodes which are overlapped to each other as an upper layer and a lower layer by way of an insulation film, and to the lower-layer side electrode of at least one electrode out of the pixel electrode and the counter electrode, projections which further project from crests of convex-portion sides of the bent portions and extend toward another electrode side are provided.

This application is a Continuation application of U.S. application Ser.No. 10/636,560 filed on Aug. 8, 2003 now U.S. Pat. No. 6,650,167.Priority is claimed based on U.S. application Ser. No. 10/636,560 filedon Aug. 8, 2003, which claims priority to Japanese Patent ApplicationNo. 2002-275033 filed on Sep. 20, 2002, all of which is incorporated byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a liquid crystal display device, andmore particularly to a liquid crystal display device of high qualitywhich enhances display quality by enhancing the numerical aperture andsuppressing regions where a domain occurs.

2. Description of the Related Art

A so-called lateral electric field type (IPS type) liquid crystaldisplay device is constituted such that on each pixel region formed on aliquid crystal side surface of one of substrates which are arranged toface each other with liquid crystal sandwiched therebetween, a pixelelectrode and a counter electrode which generates an electric fieldbetween the pixel electrode and the counter electrode are formed, andliquid crystal is activated by components of the electric fieldincluding parallel to the substrate.

In the active matrix type liquid crystal display device to which such astructure is applied, first of all, on the liquid crystal side surfaceof one substrate, respective regions which are surrounded by a pluralityof juxtaposed gate signal lines and a plurality of juxtaposed drainsignal lines which cross these gate signal lines constitute pixelregions.

Then, each pixel region includes a thin film transistor which isoperated in response to a scanning signal from the gate signal line, thepixel electrode to which a video signal is supplied from a drain signalline through the thin film transistor, and the counter electrode towhich a signal which becomes reference with respect to the video signalis supplied.

Here, the pixel electrode and the counter electrode are formed in astrip-like pattern which extends in one direction, wherein therespective electrodes are usually constituted of two or more electrodesand are alternately arranged.

Further, in such a constitution, following type of liquid crystaldisplay device is known, that is the counter electrodes are formed on anupper surface of an insulation film formed to cover also the drainsignal lines and, at the same time, the counter electrodes are formedalong the drain signal lines such that the counter electrodes have thecenter axes thereof substantially aligned with the drain signal linesand have a width larger than a width of the drain signal lines. This isbecause those lines of electric force from the drain signal lines can beeasily terminated at the counter electrodes disposed above the drainsignal lines and it is possible to prevent the lines of electric forcesfrom being terminated to the pixel electrodes. That is, when lines ofelectric forces are terminated at the pixel electrodes, this gives riseto noises.

Then, the respective counter electrodes are formed integrally withcounter voltage signal lines formed on an upper surface of theinsulation film on the same layer and reference signals are supplied torespective counter electrodes through these counter voltage signallines.

Further, there has been known a liquid crystal display device whichadopts a so-called multi-domain system in which the pixel electrodes andthe counter electrodes which are alternately arranged are formed in apattern in which these electrodes have a large L-shaped bent portion.

With respect to liquid crystal, even when the molecular arrangement isat the same state, the polarized state of transmitting light is changedin response to the incident direction of light which is incident on aliquid crystal display panel and hence, optical transmissivity differscorresponding to the incident direction of light.

Such viewing-angle dependency of the liquid crystal display panelinduces a luminance inversion phenomenon when a viewing point isobliquely inclined with respect to a viewing angle direction and hence,the liquid crystal display panel exhibits display characteristics thatimages are colored in a case of color display.

Accordingly, the pixel electrode is formed in a pattern in which atleast one bent portion is formed in the extending direction and thecounter electrode is formed in a shape which shifts this pattern inparallel, and using an imaginary line which connects bent points ofthese respective electrodes as a boundary, the direction of an electricfield acting between respective electrodes differ between one region andthe other region whereby coloring of images dependent on the viewingangle is compensated.

SUMMARY OF THE INVENTION

However, with respect to the liquid crystal display device having such aconstitution, in a design pattern of electrodes having “the L-shaped”bent portions, when etching is performed during the formation ofelectrodes, concave/convex portions of the bent portions become smoothor rounded and are formed into a shape close to a straight line. Whenthis occurs, a domain region (a region which is also referred to as adiscrimination region in which a portion which has the electric fielddirection different from the normal electric field direction is formedand hence, display is not performed normally) spreads. Further, beinginfluenced by irregularities of etching conditions, this tendency ischanged. Such a tendency becomes more apparent with the use of atransparent conductive film made of ITO (Indium Tin Oxide), ITZO (IndiumTin Zinc Oxide) as a material of the counter electrodes.

Further, it has been known that when a so-called NB (normally black)display is adopted, the domain region is displayed dark even when thisportion is subjected to bright display thus giving rise to differencewith respect to desired luminance to be displayed. Particularly, withrespect to the high-definition pixels of 200 ppi class, it is needlessto say that the adverse influence which this region occupying an openingportion of one pixel gives to the display characteristics cannot beignored.

For example, even when the pixel seems to display the normal luminancevalue, due to the influence of the domain region, the pixel isrecognized as a pixel with darkened luminance. Further, this differenceis changed in a finish pattern thus causing luminance irregularitieswithin a screen. Further, the occurrence of this domain also becomes acause for giving an adverse influence that a rising response speed ofliquid crystal molecule is lowered.

Further, although the large enhancement of numerical aperture can beexpected in the liquid crystal display system, as a byproduct, it isnecessary to overlap the counter electrode (transparent conduct film)having a width about 3 times as large as a width of the drain signalline by way of a protective film formed of an organic material layer andhence, particularly with respect to the high-definition pixels of about200 ppi, a sufficient electrode interval cannot be insured.

For example, when the drain signal line having a width of 6 μm is used,it is necessary to cover the drain signal line with the counterelectrode having a width of 18 μm. That is, when the width of thecounter electrode is narrowed, electric-field noises from the drainsignal line intrudes into the liquid crystal layer between the pixelelectrode and the counter electrode and hence, the normal luminancecurve is changed in response to signals from the drain signal linewhereby a so-called smear phenomenon that the luminance curve is changedis observed. Accordingly, although efforts have been made to relativelynarrow the drain signal line to 4–5 μm, with respect to a large-sizedpanel, there arises a drawback that disconnection of the drain signallines frequently occurs.

Further, in such type liquid crystal display device, it may be possibleto integrally form the counter voltage signal line which supplies avoltage to the counter electrode and the counter electrode. However,when the counter voltage signal line is arranged at the center of pixelregion, it is necessary to arrange a through hole formed in an organicprotective film PAS at the center portion of the screen. In this case,the disturbance of orientation or the disturbance of electric field isgenerated in this portion thus giving rise to a drawback that thecontrast is lowered and the numerical aperture is lowered in the blackdisplay.

The present invention has been made under such circumstances and it isan advantage of the present invention to provide a liquid crystaldisplay device which can enhance display quality by enhancing numericalaperture and by suppressing the occurrence of domains.

Here, designing of bent portions of comb-teeth electrodes is disclosedin Japanese Patent Laid Open 2002-40456 and Japanese Patent Laid Open2000-56320, for example.

The advantage, other advantages and novel features of the presentinvention will become apparent from the description of thisspecification and attached drawings.

To briefly explain the summary of typical inventions among theinventions disclosed in this specification, they are as follows.

(1) The liquid crystal display device according to the present inventionis, for example, characterized in that on each pixel region formed on aliquid-crystal-side surface of one substrate out of respectivesubstrates which are arranged to face each other in an opposed mannerwith liquid crystal therebetween, a pixel electrode having a bentportion and a counter electrode which is arranged at a position wherethe pixel electrode is shifted in parallel are formed, at least oneelectrode out of the pixel electrode and the counter electrode isconstituted of two electrodes which are superposed as an upper layer anda lower layer by way of an insulation film, and a projection which isfurther projected from a crest of a convex-side portion of the bentportion toward another electrode side is formed on the lower-layer-sideelectrode out of two electrodes.

(2) The liquid crystal display device according to the present inventionis, for example, characterized in that on the premise of theconstitution (1), in the lower-layer-side electrode of the anotherelectrode, a notched portion which further cuts off a bottom portion ofa concave-portion side of the bent portion is formed.

(3) The liquid crystal display device according to the present inventionis, for example, characterized in that on the premise of theconstitution (1), an insulation film interposed between two pixelelectrodes and an insulation film interposed between two counterelectrodes differ in the number of lamination.

(4) The liquid crystal display device according to the present inventionis, for example, characterized in that on a liquid-crystal-side surfaceof one substrate out of respective substrates which are arranged to faceeach other in an opposed manner with liquid crystal therebetween,regions which are surrounded by a plurality of juxtaposed gate signallines and a plurality of juxtaposed drain signal lines which cross thesegate signal lines are formed as pixel regions, a thin film transistordriven in response to a scanning signal from the gate signal line and apixel electrode to which a video signal is supplied from the drainsignal line through a drain electrode and a source electrode of the thinfilm transistor are provided to the inside of each pixel region, thedrain signal line is formed in a zigzag shape having bent portions at aportions where the drain signal line crosses the gate signal line and atleast at a substantially center portion of the pixel region, the thinfilm transistor is formed in the vicinity of the concave-portion side ofthe bent portion of the drain signal line, the drain electrode is formedof a portion of the drain signal line, and the source electrode isformed so as to face the drain electrode in an opposed manner with achannel length in the running direction of the gate signal line.

(5) The liquid crystal display device according to the present inventionis, for example, characterized in that on the premise of theconstitution (4), the source electrode of the thin film transistor isconnected to the pixel electrode, and the vicinity of the connectingportion of the pixel electrode with the source electrode includes anextension having a pattern which reduces a domain between the pixelelectrode and the counter electrode and blocks electric field noisesfrom the gate signal line by shielding.

(6) The liquid crystal display device according to the present inventionis, for example, characterized in that on the premise of theconstitution (4), the thin film transistor is arranged betweenextensions of the pixel electrode and the counter electrode which arearranged close to each other.

(7) The liquid crystal display device according to the present inventionis, for example, characterized in that on a liquid-crystal-side surfaceof one substrate out of respective substrates which are arranged to faceeach other in an opposed manner with liquid crystal therebetween,regions which are surrounded by a plurality of juxtaposed gate signallines and a plurality of juxtaposed drain signal lines which cross thesegate signal lines are formed as pixel regions, a thin film transistordriven in response to a scanning signal from the gate signal line and apixel electrode to which a scanning signal is supplied from the drainsignal line through a drain electrode and a source electrode of the thinfilm transistor are provided to the inside of each pixel region, thedrain signal line is formed in a zigzag shape having bent portions atportions where the drain signal line crosses the gate signal line and atleast at a substantially center portion of the pixel region, the thinfilm transistor is formed in a pattern in which a side of the drainelectrode which faces the source electrode in an opposed manner has aconcave portion and also in a pattern in which a side of the sourceelectrode which faces the drain electrode in an opposed manner has aconvex portion.

(8) The liquid crystal display device according to the present inventionis, for example, characterized in that on the premise of theconstitution (7), the drain electrode of the thin film transistor usesthe pattern of the bent portion of the drain signal line as it is.

(9) The liquid crystal display device according to the present inventionis, for example, characterized in that on a liquid-crystal-side surfaceof one substrate out of respective substrates which are arranged to faceeach other in an opposed manner with liquid crystal therebetween, pixelregions which are surrounded by a plurality of juxtaposed gate signallines and a plurality of juxtaposed drain signal lines which cross thesegate signal lines are formed, on each pixel region, a switching elementwhich is driven in response to a scanning signal from the gate signalline, a pixel electrode to which a video signal is supplied from thedrain signal line through the switching element, and a counter electrodewhich is connected to a counter voltage signal line and generates anelectric field between the pixel electrode and the counter electrode areformed, the counter electrode includes a lower-layer counter electrodeand an upper-layer counter electrode which is formed above thelower-layer counter electrode, the lower-layer counter electrode isformed such that the lower-layer counter electrodes are respectivelyarranged at both sides of the drain signal line through the drain signalline and a first insulation film, and the upper-layer counter electrodeis formed such that the upper-layer counter electrode covers the drainsignal line and the lower-layer counter electrodes by way of the secondinsulation film.

(10) The liquid crystal display device according to the presentinvention is, for example, characterized in that on the premise of theconstitution (9), the drain signal line and the lower-layer counterelectrodes which are arranged at both sides of the drain signal linehave bent portions and, at the same time, projections which are furtherprojected from crests at convex-sides of the bent portions of thelower-layer counter electrodes and are extended, to the pixel electrodeside are formed.

(11) The liquid crystal display device according to the presentinvention is, for example, characterized in that on each pixel regionformed on a liquid-crystals-side surface of one substrate out ofrespective substrates which are arranged to face each other with liquidcrystal therebetween, a pixel electrode having a bent portion and acounter electrode which is arranged at a position where the pixelelectrode is shifted in parallel, and a projection which is projectedfrom a crest of the convex-portion side of the bent portion of oneelectrode out of the pixel electrode and the counter electrode toward abottom portion of the concave-portion side of the bent portion ofanother electrode which faces one electrode in an opposed manner areformed, and the bottom portion of the concave-portion side of the bentportion of the another electrode is notched to form a notched portion.

(12) The liquid crystal display device according to the presentinvention is, for example, characterized in that on the premise of theconstitution (9), the respective lower-layer counter electrodes whichare arranged at both sides of the drain signal line are connected toeach other by a connector which is arranged to cross the drain signalline.

(13) The liquid crystal display device according to the presentinvention is, for example, characterized in that on the premise of theconstitution (9) or (12), the lower-layer counter electrodes are bentaway from each other such that the lower-layer counter electrodes arenot overlapped to the drain signal line at a side of the gate signalline.

(14) The liquid crystal display device according to the presentinvention is, for example, characterized in that on aliquid-crystal-side surface of one substrate out of respectivesubstrates which are arranged to face each other in an opposed mannerwith liquid crystal therebetween, pixel regions which are surrounded bya plurality of juxtaposed gate signal lines and a plurality ofjuxtaposed drain signal lines which cross these gate signal lines areformed, on each pixel region, a switching element which is driven inresponse to a scanning signal from the gate signal line, a pixelelectrode to which a video signal is supplied from the drain signal linethrough the switching element, and a counter electrode which isconnected to a counter voltage signal line and generates an electricfield between the pixel electrode and the counter electrode are formed,the counter electrode includes a lower-layer counter electrode and anupper-layer counter electrode which is formed above the lower-layercounter electrode, the lower-layer counter electrode is formed such thatlower-layer counter electrode is constituted of an intermediateconductive layer between the drain signal line and the gate signal line,is insulated from the drain signal line by way of a first insulationfilm and is insulated from the gate signal line by way of a thirdinsulation film, is arranged in the vicinity of at least one signal lineout of the drain signal line and the gate signal line, and is extendedin the extending direction of the drain signal line.

(15) The liquid crystal display device according to the presentinvention is, for example, characterized in that on the premise of theconstitution (14), the lower-layer counter electrode constitutes anoverlapped region together with the pixel electrode by way of the firstinsulation film and forms a holding capacitance in the region.

(16) The liquid crystal display device according to the presentinvention is, for example, characterized in that on the premise of theconstitution (14) or (15), the upper-layer counter electrode andlower-layer counter electrode are electrically connected to each otherover the gate signal line within the pixel region via a through hole.

(17) The liquid crystal display device according to the presentinvention is, for example, characterized in that on aliquid-crystal-side surface of one substrate out of respectivesubstrates which are arranged to face each other in an opposed mannerwith liquid crystal therebetween, pixel regions which are surrounded bya plurality of juxtaposed gate signal lines and a plurality ofjuxtaposed drain signal lines which cross these gate signal lines areformed, on another substrate, color filters having bent portions areformed within the pixel region, and projections which are furtherprojected from crests of convex-portion sides of the bent portions areformed or notched portions are formed at the concave-portion sides ofthe bent portions.

Here, the present invention is not limited to the constitution andvarious modification can be conceived without departing from thetechnical concept of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a constitutional view showing one embodiment of a pixel of aliquid crystal display device according to the present invention.

FIG. 2 is a plan view showing another embodiment of a pixel of a liquidcrystal display device according to the present invention.

FIG. 3 is a plan view showing another embodiment of a pixel of a liquidcrystal display device according to the present invention.

FIG. 4 is a plan view showing one embodiment of pixel electrodes andcounter electrodes of a liquid crystal display device according to thepresent invention.

FIG. 5 is an explanatory view for explaining the distribution of anelectric field between a pixel electrode and a counter electrode of aliquid crystal display device according to the present invention.

FIG. 6 is a plan view showing another embodiment of pixel electrodes andcounter electrodes of a liquid crystal display device according to thepresent invention.

FIG. 7 is a plan view for explaining a pattern of a pair of electrodeswhich generates an electric field of the liquid crystal display deviceaccording to the present invention.

FIG. 8 is a plan view showing one embodiment of a thin film transistorof a liquid crystal display device of the present invention.

FIG. 9 is a comparison view for showing an advantageous effect of a thinfilm transistor of a liquid crystal display device of the presentinvention.

FIG. 10 is an explanatory view for exhibiting advantageous effects of aliquid crystal display device according to the present invention.

FIG. 11 is a plan view showing another embodiment of a thin filmtransistor of a liquid crystal display device of the present invention.

FIG. 12 is an explanatory view for explaining advantageous effects of athin film transistor of a liquid crystal display device according to thepresent invention.

FIG. 13 is a plan view for showing one embodiment of the constitution ofdrain signal lines and the vicinity of the drain signal lines of aliquid crystal display device according to the present invention.

FIG. 14 is a cross-sectional view taken along a line XIV—XIV in FIG. 13.

FIG. 15 is a plan view showing another embodiment of a pixel of a liquidcrystal display device according to the present invention.

FIG. 16 is a cross-sectional view taken along a line XVI—XVI in FIG. 15.

FIG. 17 is a plan view showing the first step out of steps for showingone embodiment of a manufacturing method of a liquid crystal displaydevice according to the present invention.

FIG. 18 is a plan view showing the second step out of steps for showingone embodiment of a manufacturing method of a liquid crystal displaydevice according to the present invention.

FIG. 19 is a plan view showing the third step out of steps for showingone embodiment of a manufacturing method of a liquid crystal displaydevice according to the present invention.

FIG. 20 is a plan view showing the fourth step out of steps for showingone embodiment of a manufacturing method of a liquid crystal displaydevice according to the present invention.

FIG. 21 is a plan view showing the fifth step out of steps for showingone embodiment of a manufacturing method of a liquid crystal displaydevice according to the present invention.

FIG. 22 is a plan view showing the sixth step out of steps for showingone embodiment of a manufacturing method of a liquid crystal displaydevice according to the present invention.

FIG. 23 is a plan view showing the seventh step out of steps for showingone embodiment of a manufacturing method of a liquid crystal displaydevice according to the present invention.

FIG. 24 is a plan view showing one embodiment of the whole of a liquidcrystal display device according to the present invention.

FIG. 25 is a plan view showing another embodiment of respective bentportions of a pixel electrode and a counter electrode of a liquidcrystal display device according to the present invention.

FIG. 26 is a graph showing an advantageous effect derived from theconstitution of an electrode shown in FIG. 25.

FIG. 27 is a constitutional view for showing another embodiment of apixel of a liquid crystal display device according to the presentinvention.

FIG. 28 is a constitutional view for showing another embodiment of apixel of a liquid crystal display device according to the presentinvention.

FIG. 29 is a constitutional view for showing another embodiment of apixel of a liquid crystal display device according to the presentinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments of the present invention are explained hereinafterin conjuction with attached drawings.

Embodiment 1

<<Whole Construction>>

FIG. 24 is a plan view showing one embodiment of the constitution of thewhole liquid crystal display device according to the present invention.The drawing is drawn corresponding to an actual geometric arrangementalthough a portion thereof is depicted as an equivalent circuit.

In the drawing, there are provided a pair of transparent substratesSUB1, SUB2 which are arranged to face each other in an opposed mannerwith liquid crystal therebetween. The liquid crystal is filled andsealed in a space defined between these substrates SUB1, SUB2 using asealing material SL which also has a function of fixing anothertransparent substrate SUB2 to one transparent substrate SUB1.

One a liquid-crystal-side surface of one transparent substrate SUB1which is surrounded by the sealing material SL, a plurality of gatesignal lines GL which extend in the x direction and are juxtaposed inthe y direction and a plurality of drain signal lines DL which extend inthe y direction and are juxtaposed in the x direction are formed.

Respective regions surrounded by respective gate signal lines GL andrespective drain signal lines DL constitute pixel regions and, at thesame time, a mass of these respective pixel regions in a matrix arrayconstitute a liquid crystal display part AR.

In respective pixel regions which are juxtaposed in the x direction, acommon counter voltage signal line CL which runs within respective pixelregions is formed. The counter voltage signal line CL constitutes asignal line which supplies a voltage which becomes the reference withrespect to video signals to counter electrodes CT of respective pixelregions which will be explained later.

Each pixel region includes a thin film transistor TFT which is operatedin response to a scanning signal supplied from one-side gate signal lineGL and a pixel electrode PX to which the video signals are supplied fromthe one-side drain signal line DL through the thin film transistor TFT.

The pixel electrode PX generates an electric field between the pixelelectrode PX and the counter electrode CT connected to the countervoltage signal line CL and optical transmissivity of the liquid crystalis controlled in response to the electric field.

Respective ends of the gate signal line GL extend over the sealingmaterial SL and extended ends of the gate signal line GL constituteterminals GLT to which output terminals of a scanning signal drivecircuit V are connected. Further, input terminals of the scanning signaldrive circuit V are configured such that signals supplied from a printedcircuit board (not shown in the drawing) which is arranged outside aliquid crystal display panel are inputted thereto.

The scanning signal drive circuit V is constituted of a plurality ofsemiconductor devices, wherein a plurality of neighboring gate signallines GL which are arranged close to each other are formed into a groupand one semiconductor device is allocated to each group.

In the same manner, respective one ends of the drain signal lines DLextend over the sealing material SL and the extending ends of the drainsignal line DL constitute terminals DLT to which output terminals of avide signal drive circuit He are connected. Further, input terminals ofthe video signal drive circuit He are configured such that signalssupplied from a printed circuit board (not shown in the drawing) whichis arranged outside a liquid crystal display panel are inputted thereto.

The video signal drive circuit He is also constituted of a plurality ofsemiconductor devices, wherein a plurality of neighboring drain signallines DL which are arranged close to each other are formed into a groupand one semiconductor device is allocated to each group.

Further, the counter voltage signal lines have right-side end portionsthereof in the drawing connected in common and a connection line thereofextends over the sealing material SL and an extended end constitutes aterminal CLT. A voltage which becomes the reference with respect to thevideo signal is supplied from these terminals.

With respect to respective gate signal lines GL, in response to ascanning signal from the scanning signal drive circuit V, one of them issequentially selected.

Further, to respective drain signal lines DL, a video signal is suppliedfrom the video signal drive circuit He at the timing of selecting thegate signal lines GL.

Here, in the above-mentioned embodiment, although the scanning signaldrive circuit V and the video signal drive circuit He are indicated assemiconductor devices mounted on the transparent substrate SUB1, tapecarrier type semiconductor devices which are connected astride thetransparent substrate SUB1 and a printed circuit board may be used.Further, when a semiconductor layer of the thin film transistor TFT ismade of polycrystalline silicone (p-Si), the semiconductor element madeof polycrystalline silicon may be formed on the transparent substrateSUB1 together with a wiring layer.

<<Constitution of Pixel>>

FIG. 1 is a view showing one embodiment of the specific constitution ofthe pixel, wherein FIG. 1A is a plan view, FIG. 1B is a cross-sectionalview taken along a line b—b in FIG. 1A, and FIG. 1C is a cross-sectionalview taken along a line c—c in FIG. 1A.

On the liquid-crystal-side surface of the transparent substrate SUB1,first of all, a pair of gate signal lines GL which extend in the xdirection and are juxtaposed in the y direction are formed.

These gate signal lines GL surround a rectangular region together with apair of drain signal lines DL described later and this region isconfigured to constitute the pixel region.

Further, in portions within the pixel region which are close to the gatesignal lines GL, the counter voltage signal lines CL are formed inparallel to the gate signal line GL and these counter voltage signallines CL are formed such that each counter voltage signal line CL runsinside respective pixel regions which are juxtaposed in the x directionin the drawing.

Over the surface of the transparent substrate SUB1 on which the gatesignal lines GL and the counter voltage signal lines CL are formed, aninsulation film GI (see FIG. 1B, C) made of SiN, for example, is formedsuch that the insulation film GI also covers the gate signal lines GLand the counter voltage signal lines CL.

The insulation film GI is configured to perform a function as aninterlayer insulation film with respect to the gate signal lines GL inregions where the drain signal lines DL described later are formed and afunction as a gate insulation film in regions where the thin filmtransistors TFT described later are formed.

Then, over the surface of the insulation film GI, semiconductor layersAS made of amorphous Si, for example, are formed such that eachsemiconductor layer AS is overlapped to a portion of the gate signalline GL.

This semiconductor layer AS is a semiconductor layer of the thin filmtransistor TFT, wherein by forming a drain electrode SD1 and a sourceelectrode SD2 over the semiconductor layer AS, it is possible toconstitute an MIS type transistor structure having an inversed staggeredstructure which uses a portion of the gate signal line GL as the gateelectrode.

Here, the drain electrode SD1 and the source electrode SD2 aresimultaneously formed at the time of forming the drain signal lines DL.

That is, the drain signal lines DL which extend in the y direction andare juxtaposed in the x direction are formed, the portion of the drainsignal line DL is extended over an upper surface of the semiconductorlayer AS so as to form the drain electrode SD1, and the source electrodeSD2 is formed in a spaced apart manner by a length of channel of thethin film transistor TFT from the drain electrode SD1.

Further, the source electrode SD2 is integrally formed with alower-layer pixel electrode PXM which is formed within the pixel region.Here, the lower-layer pixel electrode PXM is arranged to be partiallyoverlapped to the upper-layer pixel electrode PX described later andhence is expressed in a distinguished manner from the upper-layer pixelelectrode PX.

That is, the lower-layer pixel electrode PXM is constituted of a groupconsisting of a plurality of electrodes (two in the drawing) whichextend in the y direction and are juxtaposed in the x direction withinthe pixel region. One end portion of one of these lower-layer pixelelectrodes PXM also functions as the source electrode SD2 and anotherend portion of one of these lower-layer pixel electrodes PXM iselectrically connected with a corresponding portion of anotherlower-layer pixel electrodes PXM.

Further, the lower-layer pixel electrodes PXM are formed in a zigzagshape in the y direction in the drawing together with the upper-layerpixel electrodes PX and the counter electrodes CT described later thusforming the constitution which adopts a so-called multi-domain system.

For example, in FIG. 1A, each lower-layer pixel electrode PXM includesthree bent portions, and on the respective bent portions, respectiveprojections CP which are further projected from convex-portion sidecrests of the respective bent portions are integrally formed with thelower-layer pixel electrode PXM, for example. The manner of operation orthe function of these projections CP are explained later.

Here, although not shown in the drawing, thin layers which are dopedwith impurities of high concentration are formed on interfaces betweenthe semiconductor layer AS and the drain electrode SD2 and the sourceelectrode SD2 and these layers function as contact layers.

With respect to these contact layers, at the time of forming thesemiconductor layer AS, for example, impurity layers of highconcentration are already formed on surfaces thereof. Accordingly, usinga pattern of the drain electrode SD1 and the source electrode SD2 formedon an upper surface of the semiconductor layer AS as a mask, the contactlayers can be formed by etching the impurity layers which are exposedfrom the pattern.

On the surface of the transparent substrate SUB1 on which the thin filmtransistors TFT, the drain signal lines DL, the drain electrodes SD1,the source electrodes SD2 and the lower-layer pixel electrodes PXM areformed, a protective film PAS is formed. The protective film PAS isserved for obviating the direct contact of the thin film transistors TFTwith the liquid crystal and is configured to prevent the degradation ofcharacteristics of the thin film transistors TFT.

Here, the protective film PAS is constituted of a sequential laminatedbody consisting of an inorganic material layer made of a material suchas SiN and an organic material layer made of a material such as resin oris constituted of only an organic material layer as shown in FIG. 1B orFIG. 1C. At least the organic material layer is used as the protectivefilm PAS for reducing the dielectric constant of the protective film.

On an upper surface of the protective film PSV, the upper-layer pixelelectrode PX, the counter electrode CT and the counter voltage signalline CLt are respectively formed. All of the upper-layer pixel electrodePX, the counter electrode CT and the counter voltage signal line CLt areformed of a light-transmitting conductive film made of ITO (indium tinoxide), ITZO (indium tin zinc oxide), IZO (indium zinc oxide), SnO₂ (tinoxide), In₂O₃ (indium oxide). This provision is made to enhance theso-called numerical aperture of the pixel.

First of all, each upper-layer pixel electrode PX is formed in anoverlapped manner on the lower-layer pixel electrode PXM except for bothend portions thereof. One end portion (an upper-side end portion in thedrawing) of the upper-layer pixel electrode PX is connected to aconnecting portion of each lower-layer pixel electrode PXM via throughholes TH1, TH2 which are formed in the protective film PAS. Due to sucha constitution, the lower-layer pixel electrodes PXM and the upper-layerpixel electrodes PX are always held at the equal potential.

In this case, each upper-layer pixel electrode PX is arranged such thata center axis thereof in the running direction is substantially alignedwith the lower-layer pixel electrode PXM and has a width larger than awidth of the lower-layer pixel electrode PXM.

Here, in this case, the projection CP which is formed on the lower-layerpixel electrode PXM is preliminarily formed such that the projection CPextends from the lower-layer pixel electrode PXM to an extent that theprojection CP is sufficiently projected from the upper-layer pixelelectrode PX.

Here, the projection CP formed in the lower-layer pixel electrode PXM isnot formed on the upper-layer pixel electrode PX. That is, although theprojection CP is formed on the lower-layer pixel electrode PXM, theprojection CP is not formed on the upper-layer pixel electrode PX.

Further, the counter electrode CT is constituted of a group ofelectrodes consisting of a plurality of (three in the drawing)electrodes which extend in the y direction and are juxtaposed in the xdirection in the same manner as the upper-layer pixel electrodes PX.Respective counter electrodes CT are arranged such that they are formedin a zigzag shape in the running direction and are in parallel with theabove-mentioned upper-layer pixel electrodes PX.

Still further, each counter electrode CT is, when viewed in plan,positioned between the upper-layer pixel electrodes PX.

That is, the counter electrodes CT and the upper-layer pixel electrodesPX are arranged in order of the counter electrode CT, the upper-layerpixel electrode PX, the counter electrode CT, the upper-layer pixelelectrode PX, . . . , the counter electrode CT from the one-side drainsignal line DL to another-side drain signal line DL at an equal intervalrespectively.

Here, the counter electrodes CT which are positioned at both sides ofthe pixel region are formed such that the counter electrodes CT areoverlapped to the drain signal lines DL. Due to such a constitution, thedrain signal lines DL are formed in a zigzag shape in conformity withthe pattern of the counter electrodes CT. Further, the counterelectrodes CT are formed in common with the corresponding counterelectrodes CT of other pixel regions which are disposed close to eachother in the x direction.

That is, the counter electrode CT is overlapped to the drain signal lineDL such that a center axis of the counter electrode CT is substantiallyaligned with a center axis of the drain signal line DL, and a width ofthe counter electrode CT is set larger than a width of the drain signalline DL. The left-side counter electrode CT which is projected withrespect to the drain signal line DL constitutes one of respectivecounter electrodes CT of the left-side pixel region, while theright-side counter electrode CT which is projected with respect to thedrain signal line DL constitutes one of respective counter electrodes CTin the right-side pixel region.

In this manner, by forming the counter electrode CT having the widthlarger than the width of the drain signal line DL above the drain signalline DL, it is possible to obtain an advantageous effect that lines ofelectric forces from the drain signal line DL are terminated to thecounter electrodes CT while obviating the termination of the lines ofelectric forces to the upper-layer pixel electrodes PX (and thelower-layer pixel electrodes PXM). When lines of electric force from thedrain signal lines DL are terminated to the upper-layer pixel electrodesPX (and the lower-layer pixel electrodes PXM), this gives rise tonoises.

Further, respective counter electrodes CT which are formed of a group ofelectrodes are integrally formed with the counter voltage signal linesCLt which are formed of the same material as the counter electrodes CTand are formed to sufficiently cover the gate signal lines GL. Thecounter voltage signal lines CLt are electrically connected to thepreviously-mentioned counter voltage signal lines CL to each other inregions not shown in the drawing.

The reason that the counter voltage signal lines CL are providedseparately from the counter voltage signal lines CLt lies in that sincethe counter voltage signal lines CLt are made of a material having largeresistance, with the provision of the counter voltage signal line CLhaving small resistance, the overall resistance can be reduced.

Below the counter voltage signal lines CL, CLt or the counter electrodesCT, the source electrodes SD2 of the thin film transistors TFT or thepixel electrodes PX are positioned. Due to such a constitution, acapacitive element Cstg which uses a gate insulation film GI as adielectric film is formed between the pixel electrode PX and the countervoltage signal line CL.

This capacitive element Cstg is configured to have a function of storingvideo signals supplied to the pixel electrode PX, for example, for arelatively long period.

Then, over the upper surface of the transparent substrate SUB1 on whichthe upper-layer pixel electrodes PX, the counter electrodes CT and thecounter voltage signal lines CLt are formed in this manner, anorientation film (not shown in the drawing) is formed such that theorientation film also covers these components. The orientation film is afilm which is directly brought into contact with the liquid crystal anddetermines the initial orientation direction of molecules of the liquidcrystal by rubbing which is applied to a surface thereof.

<<Observation>>

The pixel electrodes PX, PXM and the counter electrodes CT having theabove-mentioned constitution are configured to solve the followingrespective drawbacks with the use of projections CP formed on thelower-layer pixel electrodes PXM. That is, the above-mentionedelectrodes PX, PXM and CT can solve the drawbacks that these bentportions, compared to portions between other pixel electrodes PX, PXMand the counter electrodes CT, exhibit the larger distance and thedirection of an electric field is changed whereby a delay of responsespeed occurs or domains are generated.

Here, the reason that the projections CP are formed on the pixelelectrode PXM is to prevent a phenomenon that since the pixel electrodePXM is formed of a layer different from a layer of the counterelectrodes CT, the distance between the projection CP and the counterelectrode CT becomes close to each other thus an electricshort-circuiting is liable to be easily generated.

However, in this case, when only the lower-layer pixel electrodes PXMare formed as the pixel electrodes, the electric field generated betweenthe projections CP of the lower-layer pixel electrodes PXM and thecounter electrodes CT is surely controlled by an electric field which issubstantially perpendicular to the transparent substrate SUB1 at themost portion. This is because that with respect to an electric fieldbetween a pair of electrodes which are arranged to close each other in aplan view, by interposing the protective film PAS having a relativelythick film thickness, an electric field having components substantiallyparallel to the transparent substrate SUB1 is decreased and an electricfield in the direction having components substantially perpendicular tothe transparent substrate SUB1 is increased. In this case, the liquidcrystal in use is activated in response to an electric field havingcomponents substantially parallel to the transparent substrate SUB1 andhence, this implies that the mere provision of projections CP to thelower-layer pixel electrodes PXM cannot realize the original task.

Accordingly, in this embodiment, also over the protective film PAS, theupper-layer pixel electrodes PX having the normal pattern (a patternwhich has no projections corresponding to the projections CP) are formedin an overlapped manner on the lower-layer pixel electrodes PXM and, atthe same time, out of the electric field generated in the vicinity ofthe bent portions between the upper-layer pixel electrodes PX and thecounter electrodes CT, it is possible to ensure the components ofelectric field substantially parallel to the transparent substrate SUB1as much as possible.

Embodiment 2

FIG. 2 is a plan view showing another embodiment of the pixel of theliquid crystal display device according to the present invention andcorresponds to FIG. 1A.

The constitution which makes this embodiment different from theembodiment shown in FIG. 1A lies in that the lower-layer counterelectrode CTM is also formed by way of an insulation film below thecounter electrode CT (excluding the counter electrode CT formed over thedrain signal line DL in an overlapped manner) which is arrangedsubstantially at the center of the pixel region. Accordingly, todiscriminate the counter electrode CT and the lower-layer counterelectrode CTM, the counter electrode CT may be also referred to as theupper-layer counter electrode CT.

The lower-layer counter electrode CTM has a center axis in the runningdirection substantially aligned with a center axis of the upper-layercounter electrode CT and has a width thereof set smaller than a width ofthe upper-layer counter electrode CT.

Further, the lower-layer counter electrode CTM is provided withprojections CP which are further projected from crests of convex-portionsides at respective bent portions. These projections CP are formed suchthat the projections CP are extended from the lower-layer counterelectrode CTM to an extent that the projections CP are sufficientlyprojected from the upper-layer counter electrode CT.

The respective lower-layer counter electrodes CTM having the projectionsCP in this manner are formed on the same layer as the counter voltagesignal lines CL and are integrally formed with the counter voltagesignal lines CL.

Due to such a constitution, it is possible to decrease the domain whichis generated between the counter electrode CT which is arrangedsubstantially at the center of the pixel region and the pixel electrodePX which is arranged close to the counter electrode CT.

Embodiment 3

FIG. 3 is a plan view showing another embodiment of the pixel of theliquid crystal display device according to the present invention andcorresponds to FIG. 2.

The constitution which makes this embodiment different from theembodiment shown in FIG. 2 lies in that the lower-layer counterelectrodes CTM are formed close to the drain signal lines DL.Accordingly, due to the corresponding lower-layer counter electrodes CTMof other neighboring pixel regions in the x direction, the drain signallines DL are formed in a state that the drain signal line DL issandwiched between the lower-layer counter electrodes CTM.

Further, these lower-layer counter electrodes CTM are overlapped to theupper-layer counter electrodes CT which are formed over the drain signallines DL in an overlapped manner, whereby the lower-layer counterelectrodes CTM are formed such that they are not projected from theupper-layer counter electrodes CT.

Accordingly, since the drain signal line DL is arranged such that thedrain signal line DL is surrounded by the counter electrodes CTM, CT towhich the reference voltage is applied in three directions, it ispossible to have an advantageous effect that an electric field whichgenerates noises from the drain signal line DL can be substantiallycompletely blocked by shielding.

Further, in this embodiment, the lower-layer counter electrode CTM whichis arranged close to the drain signal line DL also includes theprojection CP which is further projected from the convex-portion sidecrest of each bent portion. The projection CP is formed such that theprojection CP is extended from the lower-layer counter electrode CTM toan extent that the projection CP is sufficiently projected from theupper-layer counter electrode CT formed over the drain signal line DL inan overlapped manner.

The respective lower-layer counter electrodes CTM having the projectionsCP in this manner are also formed on the same layer as the countervoltage signal lines CL and are integrally formed with the countervoltage signal lines CL.

Due to such a constitution, it is possible to further decrease thedomain which is generated between the counter electrode CT which isoverlapped to the drain signal line DL and the pixel electrode PX whichis arranged close to the counter electrode CT.

Embodiment 4

For example, in both of the embodiment 2 and embodiment 3, the pixelelectrode PX and the counter electrode CT have the two-layered structureinterposing an insulation film and, at the same time, the lower pixelelectrodes PXM and the lower-layer counter electrodes CTM are formed asdifferent layers by way of an insulation film (insulation film GI).

However, it is possible to form the lower-layer pixel electrode PXM andthe lower-layer counter electrode CTM on the same layer. In this case,when the projection CP of one electrode is formed in a further extendedmanner, there exists a possibility that one electrode is electricallyshort-circuited with another electrode.

This embodiment is provided for overcoming such a drawback. That is, forexample, FIG. 4A shows the bent portions and the vicinity of the pixelelectrode PX and the counter electrode CT which is disposed close to thepixel electrode PX.

The pixel electrode PX has a two-layered structure interposing aninsulation film between layers, wherein the pixel electrode PX isconstituted of the lower-layer pixel electrode PXM which is disposedbelow the insulation film and the upper-layer pixel electrode PXtdisposed above the insulation film. The counter electrode CT also has atwo-layered structure interposing the insulation film between layers,wherein the counter electrode CT is constituted of the lower-layercounter electrode CTM disposed below the insulation film and theupper-layer counter electrode CTt disposed above the insulation film.

The lower-layer pixel electrode PXM and the lower-layer counterelectrode CTM have projections CP which are further projected from theconvex-portion side crests of respective V-shaped bent portions.Further, in the concave portion of another electrode which faces theprojection CT of one electrode in an opposed manner, a notched portionDP is formed such that the notched portion DP further cuts into a bottomof the concave portion of another electrode.

Due to such a constitution at this portion, corresponding to an amountof the notched portion DP formed in the bent portion of each electrode,the spaced-apart distance between respective electrodes becomes large atthis portion. Accordingly, even when the projection portion CP of oneelectrode is further extended as shown in FIG. 4B, for example, adrawback that the extension is electrically short-circuited with anotherelectrode can be obviated.

Here, in FIG. 4B, a distal end portion of the projection CP of thelower-layer counter electrode CTM is configured to be overlapped to theupper-layer pixel electrode PXt. Due to such a constitution, it has beenconfirmed that it is further possible to have an advantageous effect insuppression of the domain region and the enhancement of the numericalaperture of the pixels.

Here, FIG. 5A, FIG. 5B, FIG. 5C are respectively cross-sectional viewsshowing the distribution of an electric field generated betweenelectrodes when the distal end of the projection CP of the lower-layerelectrodes which constitutes one electrode approaches considerably tothe upper-layer electrode which constitutes another electrode or theseelectrodes are overlapped to each other.

Here, FIG. 5A shows a case in which between the projection CP of thelower-layer electrode which constitutes one electrode and theupper-layer electrode Tt which constitutes another electrode, theprotective film PAS which is made of organic material layer isinterposed. FIG. 5B shows a case in which between the projection CP ofthe lower-layer electrode which constitutes one electrode and theupper-layer electrode Tt which constitutes another electrode, asequential laminated body consisting of a protective film PAS1 formed ofan inorganic material layer and a protective film PAS2 formed of anorganic material layer is interposed. FIG. 5C shows a case in whichbetween the projection CP of the lower-layer electrode which constitutesone electrode and the upper-layer electrode Tt which constitutes anotherelectrode, an insulation film GI having a function of a gate insulationfilm of the thin film transistor TFT and a sequential laminated bodyconsisting of a protective film PAS1 formed of an inorganic materiallayer and a protective film PAS2 formed of an organic material layer areinterposed.

In these drawings, an electric field which is generated between theprojection CP of the lower-layer electrode which constitutes oneelectrode and the upper-layer electrode which constitutes anotherelectrode is referred to a so-called fringe electric field. In thelateral electric field type liquid crystal display device in which,respective electrodes are particularly formed of a light transmittingconductive body, this fringe electric field E can effectively activatethe liquid crystal.

Further, it is confirmed that along with the increase of the thicknessof the insulation film such as the protective film or the like, thedensity of the fringe electric field E is decreased. From thisphenomenon, it is effective to narrow a distance between the projectionCP of the lower-layer electrode which constitutes one electrode and theupper-layer electrode which constitutes another electrode in order ofFIG. 5A, FIG. 5B and FIG. 5C.

Further, although FIG. 4A and FIG. 4B show the constitution in which thenotched portion DP is not formed in the electrode at a side which facesthe projection CP and constitutes the upper-layer electrode, it isneedless to say that, as shown in the corresponding FIG. 6A and FIG. 6Brespectively, a notched portion DP1 having the substantially same shapeas the notched portion DP formed in the lower-layer electrode may beformed in the upper-layer electrode PXt or CTt.

Embodiment 5

FIG. 7 is a view which shows the more specific constitution of theprojection CP of one electrode T1 and the notched portion DP of anotherelectrode T2 at the bent portion with respect to one electrode T1 andanother electrode T2 which is disposed close to one electrode T1.

In this case, the rubbing direction RD of the orientation film isaligned in the y direction in the drawing, that is, in the runningdirection of the drain signal line DL.

In this case, by setting the relationship among inclination angles(angles with respect to the y direction, θp1, θp1 in the drawing) of oneelectrode T1 and another electrode T2, an inclination angle (an anglewith respect to the y direction, θj in the drawing) at one side of theprojection CP of one electrode T1, an inclination angle (an angle withrespect to the y-direction, θd in the drawing) at one side of theprojection CP of another electrode T2 as follows, it is confirmed thatthe further advantage is obtained with respect to the suppression ofdomain region and the enhancement of numerical aperture of the pixels.

That is, the relationship in which the inclination angles θp1, θp2 areset to a value not less than 5 degree and not more than 20 degree, theinclination angle θj is set to a value not less than 30 degree and notmore than 90 degree, the inclination angle θd is set to a value not lessthan 10 degree and not more than 60 degree, and θp1, θp2<θd≧θj isestablished.

Accordingly, the direction of the electric field from one electrode T1to another electrode T2 does not exhibit an acute change in the vicinityof the bent portion and hence, the occurrence of the domain can bedrastically decreased.

In such an electrode constitution, using the bent portion as a boundary,a liquid crystal director in regions close to both sides of the bentportion is increased at portions where the angle made by the liquidcrystal director and the transmitting axis of the polarizer POL1 assumes±45°. That is, as described also in Japanese Unexamined PatentPublication 160878/1994 (FIG. 7 in the publication), in the electrodeconstitution shown in FIG. 25, for example, with respect to a risingresponse speed Tr and a threshold voltage Vth (the lowest voltageapplied between the drive electrodes necessary for moving the liquidcrystal molecules) at an intermediate gray scale display of the liquidcrystal molecules LC1, LC2 present in a gap between parallel electrodeswhere the angles θp1 and θp2 are set to θp1=θp2=15°, for example, and anintermediate gray scale display of the liquid crystal molecules LC2, LC4present in a gap between electrodes where the angles θp1 and θp2 are setto θp1=θp2=45°, both properties are also improved as shown in FIG. 26 asan angle made by the driving electric field and the initial orientationdirection (rubbing direction RD) of the liquid crystal approaches 45°from 90° and hence, the liquid crystal director can be easily rotated.In FIG. 26, a place (corresponding to LC1, LC2, LC3, L4 shown in FIG.25) is taken on an axis of abscissas and a rising response speed Tr withrespect to the threshold voltage Vth is taken on an axis of ordinates.

Further, in such a constitution, even when a black display is performedby shifting the driving electric field from an applied state to anon-applied state, on both liquid crystal molecules which are rotatablydriven in opposite directions from each other in the vicinity of thebent portion, a resilient force which makes the liquid crystal moleculesreturn to the original orientation state strongly acts and hence, therestoring force derived from the rubbing is added whereby the liquidcrystal molecules are rotated faster so as to return to the originalorientation state. In this manner, the rising response speed can beimproved. In this manner, it is possible to improve the properties ofthe liquid crystal molecules present in the gap between electrodes inwhich the main lateral-direction driving electric field is generatedand, at the same time, the domain generating region can be formed in astable manner in manufacturing and hence, the luminance in the vicinityof the bent portion can be made stable.

According to the electrode constitution of this embodiment, due to theprovision of the notched portion DP, even when the driving electrodewhich faces the conductive layer in an opposed manner is formed on thesame layer, a drawback such as the electric short-circuiting can beeliminated. Accordingly, as shown in FIG. 27, for example, some pixelelectrodes PX and some counter electrodes CT may be formed of only atransmitting conductive layer above the protective film PAS. Here, FIG.27 corresponds to FIG. 1. A position of a portion A in FIG. 27corresponds to the portion shown in FIG. 7 or FIG. 25.

However, it is needless to say that this embodiment is applicable to acase in which all of the pixel electrodes PX and the counter electrodesCT in the pixel region are respectively formed of one layer.

Further, in the same manner as the constitution on the embodiment 4,when the pixel electrodes PX and the counter electrodes CT arerespectively realized by the two-layered structure by way of theinsulation layer, it is needless to say that it is sufficient that aperiphery of an envelope pattern of two-layered conductive electrodes asviewed in plan satisfies the above-mentioned constitution.

Embodiment 6

FIG. 8 is a plan view showing another embodiment of the pixels of theliquid crystal display device according to the present invention. Thedrawing shows the detail of the thin film transistor TFT and thevicinity thereof.

In the drawing, the characteristic constitution of this embodiment liesin that the drain signal lines DL which are formed in a zigzag shape asa result of adopting the so-called multi-domain system are arranged suchthat the gate signal line GL crosses the bent portion of the drainsignal line DL and, at the same time, the thin film transistor TFT isarranged over the gate signal line GL at the concave-portion side of thebent portion of the drain signal line DL.

Further, the drain electrode SD1 of the thin film transistor TFT isconstituted of a portion of the drain signal line DL, while the sourceelectrode SD2 which constitutes a pair with the drain electrode SD1 isarranged to face the drain electrode SD1 in an opposed manner along therunning direction of the gate signal line GL. In other words, a channellength of the thin film transistor TFT is formed such that it isarranged parallel to the running direction of the gate signal lines GL.

Accordingly, the portion of the drain signal line DL which functions asthe drain electrode SD1 (portion of the bent portion) is processed suchthat the portion is arranged parallel in the y direction at the sidewhich faces the source electrode SD2 in an opposed manner and, at thesame time, the side of the source electrode SD2 at the drain signal lineDL side is formed in parallel to the y direction.

Here, the thin film transistor TFT is positioned within the extensionsof the drain signal line DL and the pixel electrode PX close to thedrain signal line DL and is set such that assuming the width of thedrain electrode SD1 as N_(D), the channel length as L and the width ofthe source electrode SD2 as W_(S), the relationship P>N_(D)+L+W_(S) isestablished. Here, P indicates the distance between outer sides of thedrain signal line DL and the pixel electrode PX.

The pixel having such a constitution can, first of all, effectivelyprevent the domain which is liable to easily occur in the vicinity ofthe gate signal line GL. At the same time, the pattern of the sourceelectrode SD2 of the thin film transistor TFT and the vicinity portionof the pixel electrode PX which is connected to the source electrode SD2can be simplified. Further, it is possible to prevent theshort-circuiting of the pixel electrode PX with other electrode withhigh probability.

That is, in the drawing, the occurrence of the domain in the pixelregion at the left side in the drawing with respect to the pixelelectrode PX is obviated using the counter voltage signal line CLt,while the occurrence of the domain in the pixel region at the right sidein the drawing is obviated using the extension J1 of the pixel electrodePX.

In this case, the extension J1 of the pixel electrode PX can make theregion defined between the pixel electrode PX and the source electrodeSD2 extend to the center side of the pixel region whereby the occurrenceof domain can be suppressed. It is needless to say that a geometricshape of the extension J1 of the pixel electrode PX is set such that thedirection of the electric field generated between the extension J1 andthe counter electrode CT arranged close to the extension J1 is definedwithout being largely different from the direction of the normalelectric field.

This implies that in the vicinity of the thin film transistor TFT wherethe respective members are arranged in a relatively complicated manner,the pattern of the pixel electrode PX in the vicinity of the sourceelectrode SD2 can be simplified and hence, the fear of occurrence ofshort-circuiting between the pixel electrode PX with other conductivelayer on the same layer can be eliminated.

Here, the geometric shape of the counter voltage signal line CLt forobviating the occurrence of domain in the pixel region at the left sideof the drawing with respect to the pixel electrode, since the countervoltage signal line CLt is formed on the protective film PAS, alsoprovides a spatial margin and hence, it gives rise to no serious problemcompared to the pattern of the pixel electrode PX in the vicinity of thesource electrode SD2. Further, as shown in FIG. 8, places where thethrough holes TH which connect the source electrode SD2 and theupper-layer pixel electrode PXt are formed can be arranged between theextension J1 and the gate signal line GL and hence, it is possible tosolve the drawback that the numerical aperture is lowered due to theoccurrence of domain in the vicinity of these places.

Here, FIG. 9 is an explanatory view which is drawn by taking a case inwhich the thin film transistor TFT is formed on the convex-portion sideof the bent portion of the drain signal line DL into consideration.Here, FIG. 9 is depicted such that the position of the thin filmtransistor TFT is changed using the constitution of the drain signalline DL and the pixel electrode PX shown in FIG. 8 as the reference.

Accordingly, in FIG. 9, in the same manner as FIG. 8, the occurrence ofdomain can be obviated by the counter voltage signal line CL at theleft-side pixel region in the drawing with respect to the pixelelectrode PX, while the occurrence of domain can be obviated by theextension J1 of the pixel electrode PX at the right-side pixel region inthe drawing.

As can be clearly understood from FIG. 9, the extension J1 of the pixelelectrode PX for obviating the domain at the right-side pixel region inthe drawing with respect to the pixel electrode PX must be extended toan extent such that the extension J1 is arranged close to the right-sidedrain signal line DL and hence, the extension J1 must be arranged closeto the gate signal line GL.

It is needless to say that the geometric shape of the extension J1 inthis case is determined on the premise that the direction of theelectric field generated between the extension J1 and the counterelectrode CT which is arranged close to the extension J1 is set withoutbeing largely different from the direction of the normal electric field.

Here, the geometric shape of the counter voltage signal line CLt forobviating the occurrence of domain at the left-side pixel region in thedrawing with respect to the pixel electrode PX is substantially equal tothe geometric shape shown in FIG. 8.

Further, by adopting the constitution shown in FIG. 8, it is alsopossible to enhance the so-called numerical aperture of the pixelsimultaneously.

That is, FIG. 10A is an explanatory view showing the pixel regiondefined between the pixel electrode PX which is connected to the sourceelectrode SD2 of the thin film transistor TFT and the drain signal lineDL which is connected to the drain electrode SD1 of the thin filmtransistor TFT.

Due to the presence of the extension J1 in the vicinity of theconnection portion between the pixel electrode PX and the sourceelectrode SD2, electric field noises e (indicated by bold-line arrows inthe drawing) from the gate signal line GL can hardly intrude the pixelregion. That is, the extension J1 is formed such that the extension J1extends to an extent that the extension J1 is arranged substantiallyclose to the counter electrode CT which is overlapped to the drainsignal line DL, whereby an intrusion path of the electric field noises eis narrowed.

Here, FIG. 10B shows a case in which the thin film transistor TFT isarranged at the convex-portion side of the bent portion of the drainsignal line DL. That is, FIG. 10B is an explanatory view which shows thepixel region defined between the pixel electrode PX which is connectedto the source electrode SD2 of the thin film transistor TFT and thedrain signal line DL which is connected to the drain electrode SD1 ofthe thin film transistor TFT.

Although, as mentioned previously, the occurrence of domain in the pixelregion at such a portion is obviated by the counter voltage signal lineCLt which sufficiently covers the gate signal line GL, to effectivelyprevent the electric field noises e from the gate signal line GL, it isnecessary to relatively largely increase a width of the counter voltagesignal line CLt at this portion.

This is because a thickness of the protective film PAS on which thecounter voltage signal line CLt is formed is relatively large and hence,to effectively obviate the electric field noises e from the gate signalline GL, it is necessary to increase the width of the counter voltagesignal line CLt correspondingly.

In this manner, it is possible to obtain the above-mentioned respectiveadvantageous effects by arranging the thin film transistor TFT to theconcave-portion side of the bent portion of the drain signal line DL.Accordingly, in this embodiment, by forming the bent portion of thedrain signal line DL also substantially at the center portion of thepixel region, it is possible to form the bent portion having the concaveportion in the same direction at the portion where each drain signalline DL crosses the gate signal line GL.

Accordingly, it is possible to arrange the thin film transistors TFT atthe same corresponding places in respective pixels.

Embodiment 7

FIG. 11 is a plan view showing another embodiment of the pixel of theliquid crystal display device according to the present invention andcorresponds to FIG. 8.

The constitution which makes this embodiment different from theembodiment shown in FIG. 8 lies in the constitution of the drainelectrode SD1 and the source electrode SD2 of the thin film transistorTFT.

First feature lies in that with respect to the drain electrode SD1, aportion of the drain signal line DL is used as the drain electrode ofthe thin film transistor TFT in its original form.

That is, the drain signal line DL is formed in a “L-shaped” patternhaving the bent portions at portions thereof where the drain signal lineDL crosses the gate signal line GL. These bent portions and the vicinitythereof are used as the drain electrodes SD1 without processing them atall. However, the vicinity CNT of the center portion of the bent portionis partially arranged in parallel in the y direction to set the channellength L to a fixed value.

On the other hand, the source electrode SD2 of the thin film transistorTFT is formed such that the side of the source electrode SD2 which facesthe drain electrode SD1 is formed in a shape which is formed by shiftingthe side of the drain electrode SD1 which faces the source electrode SD2in the x direction.

Due to such a constitution, the channel region between the drainelectrode SD1 and the source electrode SD2 is formed in an “L-shaped”pattern having bent portions so that the channel width can be increased.

Further, when the thin film transistor TFT is arranged at theconcave-portion side of the bent portion of the drain signal line DL andthe channel region is formed in an “L shape”, the directions of electriccurrents which flow inside the channel region are directed in thedirection that the electric currents are converged to each other asshown in FIG. 12A. This implies that an area of the source electrode SD2which is overlapped to the gate signal line GL can be reduced.

Accordingly, this embodiment gives rise to an advantageous effect thatthe capacitance Cgs between the gate electrode SD1 and the sourceelectrode SD2 of the thin film transistor TFT can be reduced.

On the other hand, in FIG. 12B, a case in which the thin film transistorTFT is arranged at the convex-portion side of the bent portion of thedrain signal line DL is taken into consideration. In this case, thedirections of electric currents which flow inside the channel region ofthe thin film transistor TFT are directed in the direction that theelectric currents are diffused. As a result, it is necessary to increasethe source electrode SD2 so that there is no other way but to increasethe capacitance Cgs.

Further, as described above, in the vicinity of the source electrode SD2of the thin film transistor TFT of the pixel electrode PX, it isnecessary to form the extension which blocks the electric field noisesfrom the gate signal lines GL by shielding and hence, the state in whichthe capacitance Cgs between the extension and the gate signal line GL isfurther added.

Here, in FIG. 12A and FIG. 12B, ΔCgs·off, ΔCgs·on respectively indicatea region to which the capacitance Cgs which is generated when the thinfilm transistor TFT is switched off contributes and a region to whichthe capacitance Cgs which is generated when the thin film transistor TFTis switched on contributes.

Embodiment 8

FIG. 13 is a plan view showing another embodiment of the liquid crystaldisplay device according to the present invention. Further, FIG. 14 is across-sectional view taken along a line XIV—XIV in FIG. 13.

FIG. 13 shows the drain signal line DL, the counter electrodes CTM whichare arranged at both sides of the drain signal line DL and the counterelectrode CT which is formed of a light-transmitting conductive layerwhich is arranged in an overlapped manner with the drain signal line DLand the counter electrodes CTM.

Due to such a constitution, as shown in FIG. 14, it is possible toprovide the constitution in which the electric field (electric fieldnoises e) from the drain signal line DL is terminated to the counterelectrodes CT which are arranged at both sides of the drain signal lineDL and the counter electrode CT which is formed above the drain signalline DL, while the electric field (electric field noises e) is notterminated to the pixel electrode PX arranged close to the drain signalline DL.

Further, according this embodiment, the drain signal line DL and thecounter electrodes CTM which are arranged at both sides of the drainsignal line DL are formed at different layers by way of the insulationfilm and, at the same time, the respective counter electrodes CTM whichare arranged at both sides of the drain signal line DL are electricallyconnected to each other by connectors SH which cross the drain signalline DL at a given interval in the running direction thereof thusforming a so-called ladder-like pattern.

Respective widths Wm of the counter electrodes CTM are substantiallydetermined based on the width WD of the drain signal line DL and thewidth WIT of the counter electrode CT and are usually narrower than thewidths of other electrodes.

Accordingly, to prevent the disconnection of the counter electrodes CTM,the counter electrodes CTM are formed in the ladder pattern.Accordingly, even when one counter electrode CTM is disconnected, thesignal can be supplied to a distal terminal of one counter electrode CTMthrough one of connectors which are formed with the disconnected portioninterposed therebetween, the other counter electrode CTM and anotherconnector. Due to such a constitution, it is effective to arrange theabove-mentioned connectors SH with a relatively narrow distance betweenthe connector SH and the neighboring another connector SH.

Here, although the connector SH has also a function of supplying thereference signal to the counter electrode CT of the neighboring pixelregion, the connector SH is mainly constituted to solve the drawbackattributed to the disconnection of the counter electrode CTM. This isbecause the counter electrode CTM is configured to have at least one endthereof connected to the counter voltage signal line CL for supplyingthe reference signal to the counter electrode CT of the neighboringpixel region.

Embodiment 9

FIG. 15 is a plan view showing one embodiment when the above-mentionedrespective embodiments are applied to the pixel region of the liquidcrystal display device. Further, FIG. 16A is a cross-sectional viewtaken along a line XVIA—XVIA in FIG. 15 and FIG. 16B is across-sectional view taken along a line XVIB—XVIB in FIG. 15.

In this embodiment, one pixel includes one pixel electrode PX and twocounter electrodes CT respectively arranged at the both sides of thepixel electrode PX. The lower-layer pixel electrode PXM is arrangedbelow the pixel electrode PX and the lower-layer counter electrodes CTMare arranged below the counter electrodes CT. The lower-layer counterelectrodes CTM are formed at both sides of the drain signal line DL onthe layer different from the layer of the drain signal line DL by way ofan insulation film. Further, the lower-layer counter electrodes CTM haveportions thereof connected with each other by means of the connectionportions SH which are arranged to cross the drain signal line DL.

Further, the drain signal line DL has a zigzag shape having bentportions at portions where the drain signal lines DL cross the gatesignal lines GL and the approximately center of the pixel region. A thinfilm transistor TFT which is arranged on the gate signal line GL isarranged close to the concave-portion side of the bent portion of thedrain signal line DL.

Further, in FIG. 15, members indicated by SOC are so-called columnarspacers. As shown in FIG. 16B, the columnar spacers SOC are spacerswhich are made of resin, for example, and are formed on theliquid-crystal-side surface of the transparent substrate SUB2. Due tothese columnar spacers, a layer thickness of the liquid crystal ismaintained uniform.

This columnar spacers SOC are formed on an upper surface of the blackmatrix BM and a leveling film OC which are sequentially formed on thesurface of the transparent substrate SUB2.

The respective steps of one embodiment of the manufacturing method ofthe liquid crystal display device having such a constitution areexplained hereinafter in conjunction with FIG. 17 to FIG. 23. Here, aphotolithography method is performed once in each step shown in eachdrawing and hence, the pixel regions of the transparent substrate SUB1side can be formed by performing the photolithography method seven timesin total.

Step 1. (FIG. 17)

First, the gate signal lines GL are formed on the liquid crystal-sidesurface of the transparent substrate SUB1. As the material of this gatesignal line GL, for example, a laminated body which is formed bylaminating a Mo—Cr layer or a Mo—Zr layer having a thickness ofapproximately 60 nm to the Al—Nd layer having a thickness ofapproximately 250 nm is used.

In addition, it is needless to say that the gate signal line GL may havea so-called anodized film formed on the surface thereof.

Thereafter, an insulation film GI is formed over the transparentsubstrate SUB1 such that the insulation film GI also cover the gatesignal line GL. This insulation film GI becomes a gate insulation filmof the thin film transistor TFT and hence, a film thickness of theinsulation film GI is set to have the function as a gate insulationfilm. As the material of the insulation film GI, for example, a siliconnitride film (SiN) having a thickness of approximately 350 nm is used.

Further, an amorphous silicon (a-Si) layer AS having a thickness ofapproximately 200 nm is formed on a surface of the insulation film GIand a highly concentrated N⁺ impurity layer is formed on a surface ofthe amorphous silicon layer AS by doping the surface with phosphorous.

In addition, by sequentially forming the insulation film GI and theamorphous silicon (a-Si) layer AS collectively using a same bell jar bya CVD method, for example, the step can be performed reliably whilepreventing the intrusion of impurities.

Step 2 (FIG. 18)

Then, the amorphous silicon layer AS is formed in a given pattern. Here,the amorphous silicon layer AS is made to remain not only in the regionfor forming the thin film transistor TFT but also in the region forforming the pixel electrode PX. This provision is for preventingbreaking of the pixel electrode PX which is formed later due to astepped portion.

Step 3. (FIG. 19)

Next, the counter voltage signal lines CL, the counter electrodes CTMconnected to the counter voltage signal lines CL, the drain electrodesSD1 and the source electrodes SD2 of the thin transistors TFT areformed. As the materials of the counter voltage signal lines CL, thecounter electrodes CT, the drain electrodes SD1 and the sourceelectrodes SD2, for example, any one of Mo—Cr, Mo—Zr, Ta, Ti, Cr and thelike can be used. With regard to the film thickness of the countervoltage signal line CL, the counter electrode CT, the drain electrodeSD1 and the source electrode SD2, it is appropriate to set the filmthickness to about 120 nm.

Using the drain electrode SD1 and the source electrode SD2 of the thinfilm transistor TFT as masks, the N-type impurity layer on an uppersurface of the amorphous silicon layer AS which is exposed from themasks is removed by etching.

Then, the protective film PAS1 is formed on a surface of the transparentsubstrate SUB1 such that the protective film PAS1 also covers thecounter voltage signal lines CL and the counter electrodes CTM. As thematerial of the protective film PAS1, a silicon nitride film (SiN) isused, for example, and the appropriate film thickness is about 200 nm.

Step 4. (FIG. 20)

Through holes TH are formed in the protective film PAS1 and, via thesethrough holes TH, portions of the drain electrodes SD1 and portions ofthe source electrodes SD2 of the thin film transistors TFT are exposed.

It is preferable that these through holes TH are formed by dry etching.In this case, it is also preferable to form the through holes at theterminal portions of the gate signal lines GL and the drain signal linesDL simultaneously.

Step 5 (FIG. 21)

Next, the drain signal lines DL, the lower-layer pixel electrodes PXMand the conductive layers are formed. Here, the conductive layers areformed on portions which face the columnar spacers.

As the material of the drain signal lines DL, the lower-layer pixelelectrodes PXM and the conductive layers, a laminated body which isformed by sequentially laminating, for example, a Mo—Cr layer or a Mo—Zrlayer having a thickness of approximately 60 nm, an Al—Nd layer having athickness of approximately 250 nm, a Mo—Cr layer or a Mo—Zr layer havinga thickness of approximately 60 nm is used.

Step 6 (FIG. 22)

The protective film PAS2 is formed. This protective film PAS2 isconstituted of an organic material layer and is preferably formed by acoating method. The appropriate thickness of the protective film pAS2 isabout 2000 nm. Then, by forming through holes TH in the protective filmPAS2, portions of the extensions of the portions of the pixel electrodesPXM which are connected to the source electrodes SD2 of the thin filmtransistors TFT are exposed.

Step 7. (FIG. 23)

On the surface of the protective film PAS2, the counter electrodes CT,the counter voltage signal lines CLt and the upper-layer pixelelectrodes PX are formed. As the material of the counter electrodes CT,the counter voltage signal lines CLt and the upper-layer pixelelectrodes PX, for example, a conductive layer having nonlight-transmitting property such as ITO (Indium Tin Oxide), ITZO (IndiumTin Zinc Oxide) or the like is used.

Embodiment 10

FIG. 28 is a plan view showing another embodiment of the pixel of theliquid crystal display device according to the present invention andcorresponds to FIG. 21, for example.

In this embodiment, when a short-circuited portion (for example,indicated by a T portion in the drawing) is formed between the counterelectrode CTM and the drain signal line DL which is formed over thecounter electrode CTM by way of the insulation layer, it is possible torepair the short-circuited portion using laser beams such that thedisplay is not influenced. That is, portions of the conductive layer ofthe counter electrode CTM are arranged in the vicinity of the gatesignal lines thus forming portions which are not overlapped to the drainsignal lines and these portions C1, C2, C3, C4 are cut.

Further, when a portion where the drain signal line DL is disconnected(for example, indicated as a portion K in the drawing), the portions C1,C2, C3, C4 are cut by the laser beams and, thereafter, the laser beamsare radiated to the short-circuited portions S1, S2, whereby the drainsignal line DL is electrically connected to the portion which was thepattern of the counter electrode CTM.

Embodiment 11

FIG. 29 is a plan view showing another embodiment of the pixel of aliquid crystal display device according to the present invention andshows the constitution of color filters FIL formed on theliquid-crystal-side surface of the transparent substrate SUB2.

In the drawing, the black matrix BM has a pattern extending along thegate signal line GL and each color filter FIL is formed having bentportions in an L shape along the drain signal line DL. In conformitywith the shape of the bent portions of the drain signal line DL, also onthe bent portions of the above-mentioned color filter FIL, theprojections CPF which are further projected from the convex-portion-sidecrests of the bent portions are formed. Alternatively, the notchedportions DPF may be formed in the concave-portion side of the bentportion.

Due to such a constitution, leaking of light can be eliminated and adesired liquid crystal gap can be obtained.

The above-mentioned respective embodiments can be used individually orin combination. This is because the advantageous effect of therespective embodiments can be performed individually or in a combinedform.

As can be clearly understood from the above explanation, the liquidcrystal display device according to the present invention can improvethe numerical aperture, can suppress the generation of the domain andcan improve the display quality.

1. A liquid crystal display device comprising: a pair of substrates with a liquid crystal layer therebetween; a pixel electrode and a counter electrode formed on one of said pair of substrates; wherein said pixel electrode is formed in a zigzag shape having a plurality of V-shaped bent portions a convex-portion side of each V-shaped bent portion has a projection portion which is further projected from a crest of said convex-portion side of said each V-shaped bent portion, and a concave-portion side of said each V-shaped bent portion has a notched portion which further cuts into a bottom of said concave-portion side of said each V-shaped bent portion.
 2. A liquid crystal device according to claim 1, wherein the pixel electrode and the counter electrode are transparent.
 3. A liquid crystal display device comprising: a pair of substrates with a liquid crystal layer therebetween; a pixel electrode and a counter electrode formed on one of said pair of substrates and have a space in plan view therebetween; wherein said space is formed in a chevron shape pattern with a convex-portion side, a concave-portion side, a projection portion which is further projected from a crest of a convex-portion side of said chevron shape, a notched portion which further cuts into a bottom of said concave-portion side of said chevron shape. the convex-portion side and the concave-portion side of said chevron shape pattern have inclination angles of θ p1 and θ p2 with respect to a rubbing direction of an orientation film, said notched portion and said projection portion have inclination angles of θ d and θ j with respect to the rubbing direction, and having the relation of θ p1<θ d, θ p1<θ j, θ p2<θ d, and θ p2<θ j.
 4. A liquid crystal display device comprising: a pair of substrates with a liquid crystal layer therebetween; a pixel electrode and a counter electrode formed on one of said pair of substrates; wherein the pixel electrode and the counter electrode are consist with an upper-layer electrode and a lower-layer electrode with an insulating layer therebetween, and the pixel electrode and the counter electrode are in a zigzag shape having a bent portion.
 5. A liquid crystal display device according to claim 4, wherein the upper-layer electrode is transparent conductive layer and wider than the lower-layer electrode.
 6. A liquid crystal display device comprising: a pair of substrates with a liquid crystal layer therebetween; a pixel electrode and a counter electrode formed on one of said pair of substrates; wherein the counter electrode have an upper-layer electrode and a lower-layer electrode, the upper-layer electrode is positioned at a layer over a drain signal line with a first insulating layer therebetween and overlaps with the drain signal line, the lower-layer electrode is positioned at a layer below the drain signal line with a second insulating layer therebetween and extends along the upper-layer electrode with an overlapping relation.
 7. A liquid crystal display device according to claim 6, wherein the lower-layer electrode is formed at a both sides of the drain signal line and edges of the lower-layer electrode are inside of the upper-layer electrode.
 8. A liquid crystal display device according to claim 6, wherein the upper-layer r electrode is transparent conductor and overlaps with a gate signal line with the first insulating layer and the second insulating layer therebetween. 